1. Field of the Invention
This invention relates to electronic systems, and more particularly, to clock and power failure protection for ensuring reliability of electronic systems.
2. Description of the Related Art
High availability computer systems such as file servers typically require reliable power and clocking. Power and/or clock failures may result in system down time. In some systems, even a momentary interruption in power or clocking may result in a system crash. In order to prevent system down time, redundancy may be built into the power and/or clocking circuitry.
Redundancy for power distribution systems may include using multiple power sources to supply a computer system. Additional redundancy may be attained by using multiple boards for power distribution within the computer system. The boards may include detection circuitry, which may be configured to detect the presence of power from the other board. One of the boards may act as a primary power distribution board, while one or more additional boards may act as secondary power distribution boards. If the primary power source or the primary power distribution board fails, one of the secondary power distribution boards may take over the duties of supplying power.
Redundancy for clocking of a computer system may be provided in a similar manner, using multiple clock boards. Each of the clock boards may include detection circuitry for detecting the presence of a clock signal which is provided to the computer system. One clock board may act as a primary clock board, with one or more clock boards acting as secondary clock boards. If the primary clock board fails, one of the secondary clock boards may detect this failure and take over as the primary clock board.
Companies that design and build computers are under constant demand to provide more functionality. Similarly, there is a constant demand to keep power consumption low or within certain limits. Due to these conflicting demands, it has become increasingly difficult to provide the desired redundancy for many computer systems, including those requiring high-availability. Many computer systems for which protection is desired may be so complicated that straightforward design for redundancy may compromise the cost, the design efficiency, or both.